Plaster cutting tool



April 22, 1941; E. AMUNDSEN I PLASTERCUTTING TOOL Filed Dec. 26, 1939flrizeaf flmwnalsen/ Patented Apr. 22, 194i UNITED STATES PATENT OFFICEPLAsTElfiifi sfN G TOOL Ernest Amundsen, New York, N. Y.

5 Claims.

This invention relates to a plaster cutter or plaster cutting tool andit is one object of the invention to provide a tool which will be foundvery useful by plasterers, and by means of which plaster may be outalong a crack in a wall to open the crack and thus form a crevice ofsuch width and depth that plaster may be applied and firmly held inplace for closing the crack when it has set and hardened.

Another object of the invention is to provide a tool of this characterwhich may be easily held in a persons hand and moved along a crack in awall, first with a blade presented in engagement with the Wall topenetrate the plaster and deepen and somewhat widen the crack, anotherblade being then disposed in position to enter the deepened crack andnot only additionally widen the crack or crevice but also slice throughplaster along the sides of the crack and undercut the crack. It willthus be seen that a crevice of suificient width to receive plaster maybe formed and this crevice undercut so that when plaster is forced intothe crevice with a trowel and allowed to harden, the applied plasterwill be of dovetailed formation in cross section and prevented fromworking loose and dropping out of place.

A further object of the invention is to provide a plaster cutting toolwhich is so formed that it may be very easily held in a persons hand andprevented from turning in the hand while it is to provide a plastercutting tool which is of unitary construction and includes a shankhaving a head at its front end formed with blades disposed in suchrelation to each other that one blade will not be in the way whenanother is in use.

The invention is illustrated in the accompanying drawing, wherein:

Figure l is a perspective view of the plaster cutting tool.

Figure 2 is a side elevation of the plaster cutting tool.

Figure 3 is a view looking at the-head of the tool from the left ofFigure 2.

Figure 4 is a view looking down upon the head of the tool.

This improved plaster cutting tool has a head I formed with a widenedand flattened lower portion or neck 2 from which extends a shank 3 ofsuch length that it may be conveniently held in a persons hand. Theshank i tapered to a point 4 at its lower end so that it'may be driveninto a handle if so desired.

A blade 5 is carried by the head I and extends 1 from one side of theouter end of the head at an angle of approximately forty degrees. Thiblade is of triangular formation and, while it tapers cause the blade topenetrate the plaster and form a deep and wide channel or recess.

At the opposite side of the head from the blade 5, there has been formeda blade 9 reinforced by a depending web It which is integral with theblade and constitutes part of the blade. The blade and its web H3 havetheir opposed side faces concaved, as shown at H, and, upon reierring toFigure 3, it will be seen that the side faces of the web convergedownwardly tointersect and form a diagonally extending cutting edge 12,shoulders l3 and H1 being formed at the upper and lower ends of thecutting edge I2. The blade 9 projects forwardly beyond the shoulder l3of the web to provide a spur 15 having converging side edge faces [6which intersect to form a sharp point for the outer end of the spur. Theupper face of the blade 9 and its spur it are curved longitudinally, asshown in Figure 2, thus permitting rocking motion to be imparted to thetool when the blade 9 is in use, if so desired. As the side edges of theblade 9 are sharp, these edges may be used for cutting or scrapingduring use of the tool.

When the tool is in use, it is held in a persons hand with a fingerengaging the flattened portion 2. The point 8 of the blade is applied tothe wall at the crack in the plaster and the tool moved along the crack.During this movement, the blade penetrates the plaster and, as it is oftriangular shape, the crack will be widened and deepened to'form achannel or crevice of sufiicient depth to hold plaster. The tool is thenturned to bring the blade 9 into position for use and moved through thecrevice longitudinally thereof, and during this movement, the prong IEwill serve to out out the inner portion of the crevice and the sharpedge it will serve to trim the side walls of the crevice. Therefore, thecrevice may be undercut to form a crevice having a restricted mouth and,when plaster is applied to fill the crevice and allowed to set andharden, the crevice will be filled with a hard plastic filling which issubstantially dovetailed in cross section and'thus prevented fromworking loose and dropping out of the crevice. The fact that the sidefaces of the blade 9 and the web are concaved permits undercutting to bevery effectively carried out and since the upper face of the blade iscurved longitudinally, permits rocking motion to be imparted to the toolfor ejecting hard lumps of plaster pried loose during formation of thecrevice. If so desired, the prong [5 may be first disposed in engagementwith the Wall and moved along the crack to form a shallow groove whichwill then be widened and deepened by the blade 5 to form a crevice whichis to be dug out and undercut by means of the blade 9, the spur l5 andthe sharpened edge E2 of the Web, 7

Having thus described the invention, what is claimed is:

1. A tool of the character described comprising a head having aflattened lower portion for engage nent by a finger and a shankextending therefrom, said head defining a laterally extending blade anda web under the blade, the blade and web having concaved side facesconverging downwardly and intersecting to form a diagonally extendinglower cutting edge for the web, said blade having a longitudinallycurved upper surface and having its outer portion projecting beyond theweb to form a spur tapered to a point at its outer end.

2. A tool of the character described comprising a head, said headdefining a laterally extending blade having. a depending Web formedintegral therewith and terminating in spaced relation to the outer endof the head, the blade and head having concaved side faces convergingdown wardly and intersecting to form a sharp lower edge extendingoutwardly at an upward incline, the protruding outer portion of saidblade constituting a spur gradually reduced in thickness and having itsside edge faces converging and intersecting at its outer end to form asharp point.

3. A tool of the character described comprising a head, said headdefining a laterally extending blade and a depending web under theblade, said blade and web having concaved side faces convergingdownwardly and intersecting to form a sharp cutting edge along the lowerend or the web, and said blade being formed with a longitudinallyconvexed upper face and having its outer end portion projecting beyondthe web and forming a spur having side edge faces converging andintersecting at the outer end of the spur to form a sharp penetratingpoint.

4. A tool of the character described Comprising a head, a shankextending from the rear end of said head, said head defining a laterallyextending blade having a longitudinally curved outer end face, and a.Web formed integral with said blade and the shank in depending relationto the blade, the blade and web having concaved side faces convergingdownwardly and intersecting to form a sharp cutting edge along the loweredge of the web.

5. A tool of the character described comprising a head, a shankextending from the head, said head being formed with a laterallyextending blade tapered to a point at its outer end, and a web dependingfrom said blade and sharpened along its lower edge.

ERNEST AIMUNDSEN.

